Broken rings - which route

[engineermike]

Feel free to lmk why all those cars above even though low compression via OEM aren’t putting down blistering numbers on pump gas even when pullied to 15+ psi

I thought I had explained this well enough before, but I guess I'll give it another go.

Lowering the compression a finite amount doesn't give you infinite boost tolerance and power-making potential. In fact, its very easy for me to calculate what the pump gas limit is at any compression ratio, displacement, and basic engine architecture. The Predator is very close to the reliability limit right off the showroom floor. The Redeye and Demon are not as close so there's some room to tweak those up a bit without giving up much reliability. The Trinity is actually a fair amount below it's limit so there is some room to increase boost and power, but also not out to infinity. If you want to make significantly more power reliably on pump gas with the Redeye, Demon, or Predator, you'd have to drop below 9.5/1.

Remember the old Ferrari F40? That thing made 163 hp/liter using 1980's engine management, a number that even the Predator doesn't beat with 40 years advancements, and it did it with 7.7/1 compression. Are you familiar with Mercury Marine's 1350 hp stern-drive? It makes 1350 hp on 91 reliably for hours on end at WOT due to 7.8/1 compression. The examples are endless. I could tell you about what the limit is of the Coyote (or Predator) at 9/1, 8/1, or even 7/1 compression and it's progressively higher.

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[engineermike]

Car is also more reliable on E85...

That's exactly correct. At high compression and boost, E85 is a way to make it reliable and go fast. But I've said from the beginning and the OP stipulated that he's not running E85.

.... Lol since reliability is what we’re after here, not going fast.

Who said that? I've stated from the beginning that on pump gasoline, lower compression and more boost will get you more power and reliability. You're mis-representing what I am saying and also acting like the two are mutually exclusive.

 

[80FoxCoupe]

That's exactly correct. At high compression and boost, E85 is a way to make it reliable and go fast. But I've said from the beginning and the OP stipulated that he's not running E85.



Who said that? I've stated from the beginning that on pump gasoline, lower compression and more boost will get you more power and reliability. You're mis-representing what I am saying and also acting like the two are mutually exclusive.

Mike, great argument but we are not your target audience. Maybe the OP "possibly" has an interest in lowering compression. Doubtful though.

 

[SolarFlare]

That's exactly correct. At high compression and boost, E85 is a way to make it reliable and go fast. But I've said from the beginning and the OP stipulated that he's not running E85.



Who said that? I've stated from the beginning that on pump gasoline, lower compression and more boost will get you more power and reliability. You're mis-representing what I am saying and also acting like the two are mutually exclusive.

ANY boosted motor is waaay more reliable on E85 than pump gas.

10:1 and 10psi and pump gas would get you more power than 11:1 4psi and E85 maybe. Lol

11:1 at 13psi on E85 is a more reliable car and more powerful in every way than 10:1 at 13-14psi on pump. E85 is infinitely better fuel than pump. I’m seen logs of friends of cars leaning out to 1.00 lambda at 7500 + 11:1 compression cars at 12+ psi and not show any Knock

 

[Woopaloop]

25k miles at 700 rwhp hard driving, that engine owes you nothing lol. I think it's crazy that it held together that long stock block. Hopefully you can get it back up and running for the summer.

 

[SolarFlare]

Like 80 said. It’s best to let it go. You won’t convince me dropping compression is a good idea on a daily non-raced car that ls on pump gas, meth and seeing relatively low boost.

 

[engineermike]

Mike, great argument but we are not your target audience....

You don't say. Where in the last 5 pages have I tried to convince you or 80fox to switch to 93 and drop compression? My very first post in this thread (#7) was to ask what fuel. If the answer was E85, I wouldn't have made another post. You like E85 and I've never tried to talk you out of it or said it wasn't good for power or reliability. I would say that this thread isn't your thread because you're so very invested in E85 and setting up the engine for that. However, you seem to think that an E85 engine combination is also good for other fuels with less detonation resistance. That's simply not the case. Just like diesel engines are different from gasoline, so is E85. What works well for one isn't necessarily optimized for the other. I suggest you bring your argument into an E85 vs 93 thread. That would be your target audience for much of your argument. My posts have been directly applicable to the intent of the OP, which asks what changes would you make to a new short block supercharged coyote not running E85.

ANY boosted motor is waaay more reliable on E85 than pump gas.

10:1 and 10psi and pump gas would get you more power than 11:1 4psi and E85 maybe. Lol

11:1 at 13psi on E85 is a more reliable car and more powerful in every way than 10:1 at 13-14psi on pump. E85 is infinitely better fuel than pump. I’m seen logs of friends of cars leaning out to 1.00 lambda at 7500 + 11:1 compression cars at 12+ psi and not show any Knock

I can't tell if this is an intentional straw-man argument or if you legitimately don't understand a word of my posts. This thread is not about E85 vs 93 and I have not argued that E85 is inferior for power or reliability. It's just not for everyone and the OP ruled it out on Page 1 post 8.

Like 80 said. It’s best to let it go. You won’t convince me dropping compression is a good idea on a daily non-raced car that ls on pump gas, meth and seeing relatively low boost.

So where is the break-point for you? What if the motor were 13/1 and the only fuel available is 87 octane? If you added boost, would you not support lowering compression on that one? What about 14/1 and 85 octane? Is there any case where you would admit lower compression is better suited to boost and pump gasoline? Why do you suppose all automotive OEMs and their performance divisions, marine outboard, marine inboard, PWC, UTV, and snowmobile companies all lower compression when they add boost on pump gasoline?

 

[SolarFlare]

There’s no situation where I would rely solely on 93 octane on a built high hp boosted car.

 

[DavidHuff]

There’s no situation where I would rely solely on 93 octane on a built high hp boosted car.

I agree 100%,I always know what fuel is in my 2017 Whipple Mustang.
I run a a Whipple Tune made for 93 pump gas, but I always run pump gas with VP Racing Unleaded Additive for safety or VP Racing Unleaded MS109 Racing Fuel /Pump Gas mix 50/50 if I am going full boost at the track.That setup has been great and mustang runs perfect.

 

[SolarFlare]

Exactly. I like to know whats in it. Ive been boosted for over 3 years and not once did I make a pull on solely 93 octane after my street logs. Car was tuned on 93 for a bit, 16-17* of timing and in all the logs I did I never saw knock but after Lund said ok its good to go, I added some octanium or torco whenever I was gonna play on the street. EVERY. SINGLE.TIME. Is it still running because of this or because I am lucky? IDK, Im thankful its still good and will continue my habits.

 

[gimmie11s]

No one has mentioned some of the other downsides of lower compression vs same engine with higher comp.

Some easy ones are

--Lower compression motors are lazier off boost.
--They arent as fuel efficient
--They run hotter
--Lower compression means the power is made higher in the RPM band and if turbo, boost is achieved later
--More torque is created in higher compression motor sooner

 

[ahl395]

Ya'll waste too much time arguing with strangers online. Let it go lol

 

[SolarFlare]

No one has mentioned some of the other downsides of lower compression vs same engine with higher comp.

Some easy ones are

--Lower compression motors are lazier off boost.
--They arent as fuel efficient
--They run hotter
--Lower compression means the power is made higher in the RPM band and if turbo, boost is achieved later
--More torque is created in higher compression motor sooner

Welcome to the shit list with that post LMAO

 

[gimmie11s]

Welcome to the shit list with that post LMAO

Ha! You know i love being on the shit list

 

[engineermike]

Welcome to the shit list with that post LMAO

Not at all. @gimmie11s made technical points that are each worth discussing and they were all relevant to the topic of the thread. Notice he did not deny that lower compression on pump gas can get you more power and better reliability. He also did not argue against a straw-man for the benefits of increasing octane or E85.

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